Meat processing operations include a wide variety of processing steps for preparing meat products for consumers. After slaughter, the animal carcass is cleaned, chilled, and then passed on to trimming operations in which large cuts of meat such as steaks, roasts, and filets are separated from the carcass. Special processing steps may be applied to the material left after the initial trimming operations to recover additional lean meat from the trimmings.
It may be desirable in some meat processing operations to effect a change in the pH of the meat products by adding appropriate pH modifying processing aids. For example, U.S. Pat. No. 5,871,795 discloses a process for modifying the pH of meat products using pH modifying gases, particularly ammonia gas and carbon dioxide gas, for the purpose of reducing microbe counts in the meat products. The pH modification disclosed in this patent is accomplished by placing the pH modifying gas in contact with the surface of the meat product at a pressure above the vapor pressure of the gas at the temperature of the meat product.
The process described in U.S. Pat. No. 5,871,795 may be applied to finely comminuted meat such as ground beef or to more coarsely comminuted meat such as steaks, roasts, or filets. U.S. Pat. Nos. 6,387,426 and 6,142,067 both disclose other processes for applying a pH increasing materials to meat. The process disclosed in U.S. Pat. No. 6,387,426 is suited particularly for treating larger cuts of meat, while the process disclosed in U.S. Pat. No. 6,142,067 is suited only for treating finely comminuted meat such as ground beef.
The prior pH treatments described in U.S. Pat. Nos. 5,871,795, 6,142,067, and 6,387,426 apply the pH modifying agent at the surface of the material being treated. For example, the treatments disclosed in U.S. Pat. Nos. 5,871,795 and 6,142,067 for finely comminuted or ground meat products apply the pH modifying material to the surface of the individual pieces of comminuted meat. The processes then increase the pressure on the meat product and pH increasing material and/or further comminute the meat product to distribute the pH modifying material. For larger or more coarsely comminuted cuts of meat such as steaks, roasts, or filets, the prior pH modification process shown in U.S. Pat. No. 6,387,426 applies the pH modifying material to the surface of the meat and then drives the pH modifying material into the meat by increasing the pressure on the meat.
The systems and methods set out in the above-described patents are effective for modifying the pH at the surface of the meat product and somewhat below the surface. Surface pH modification was emphasized because microbes are generally only present at the surface of the meat, and the purpose of the pH modification was mostly to reduce microbe counts. The prior pH modifying systems were generally not as effective at modifying the pH of the meat product beyond a thin surface layer on each respective piece of meat. Thus, the interior areas of larger cuts of meat such as steaks, roasts, filets, and larger carcass portions remain generally unaffected by the prior art pH treatments.